Pipe coupling

ABSTRACT

There is disclosed a pipe coupling ( 13 ) for coupling the ends of pipe sections ( 10  and  11 ) together end to end. The coupling includes a barrel member ( 19 ) adapted to bridge and surround the ends of the pipe sections to be coupled, and, together with coupling members ( 20 ), adapted to engage the ends of the barrel sections, and elastomeric sealing rings ( 21 ) adapted to be forced by the coupling members into the ends of the barrel member and expanded radially outwardly and inwardly into tight sealing engagement within the end of the barrel member and around the circumferences of the pipe sections being coupled. Substantially tangentially extending bolts ( 22 ) are utilised to couple the respective coupling members to the barrel member, and means ( 29, 30 ) on the inside of the coupling members, and on the outside of the barrel member, to interact and progressively twist the coupling members along the barrel member to force the sealing rings into tight sealing engagement with the inside of the barrel member and around the circumference of the pipe sections being coupled. There is also disclosed a coupling which has a barrel member which forms part of one of the pipe sections to be joined and only one coupling member and sealing ring is used to couple the barrel member to the other pipe section.

TECHNICAL FIELD

This invention relates to pipe couplings for joining the ends of pipe sections end to end in pipelines, and more particularly, but not exclusively, for use in replacing burst pipeline sections in water pipelines. The pipe coupling may be for the purpose of joining directly abutting pipe ends, although the coupling is also applicable to the joining of pipe ends of various configurations such as socket and spigot joints.

The invention has been particularly developed for coupling the ends of a replacement pipe section to the ends of an existing pipe after a burst section of pipe has been removed, such as in a water main pipeline extending beneath or adjacent roadways in commercial and/or residential locations.

BACKGROUND ART

In order to replace burst sections of such water supply pipelines, a trench or hole is dug down to and along the burst section of the pipeline. The burst section is then cut out from the pipeline and replaced with a new pipe section which is to be coupled at both ends to the ends of the existing pipeline by couplings.

Known, but not necessarily commonly known, couplings have a barrel section bridging and surroundings the ends of the old and new pipeline sections, with the barrel receiving at both ends elastomeric sealing rings to form a seal between the inside of the barrel and the circumferences of the existing and new pipe sections. The sealing rings are of an axially tapered configuration and are forced into matingly internally tapered ends of the barrel by annular cylindrical coupling members surrounding the respective pipe sections and axially connected by bolts extending through lugs in the coupling members at each end of the coupling and along the length of the barrel. The bolts when tightened progressively force the sealing rings into the opposite ends of the barrel whilst compressing the sealing rings to expand them radially outwardly into tight sealing engagement within the ends of the barrel and radially inwardly into tight sealing engagement around the circumferences of the pipe sections being joined. A similar coupling is used to couple the opposite end of the new pipe section to the adjacent end of the existing pipe section. Multiple axially extending bolts are utilised equally spaced around the coupling to provide an even distribution of force on the sealing rings. There may be up to sixteen, or even more, axially extending bolts.

However, because of the location of the connecting bolts with such known couplings, access to beneath the pipe sections is required when tightening the bolts, thus producing back strain, whilst, because of the number of bolts to be tightened, the task of installing the coupling can be time consuming.

It is therefore an object of the present invention to provide a coupling which overcomes, or at least minimises, the above disadvantages with known couplings, whilst also accommodating different diameters of pipe sections to be coupled and also differences between the diameters of the existing pipe and the diameter of the new pipe section. For example the existing pipe may be a metal pipe and the new replacement pipe section may be PVC having a thinner wall thickness, but providing an internal diameter the same as that of the existing pipe but with a smaller external diameter.

DISCLOSURE OF THE INVENTION

In accordance with the present invention there is provided a pipe coupling for coupling the ends of pipe sections together end to end, said coupling including a barrel member forming part of the end of one of the pipe sections, or adapted to bridge and surround the ends of the pipe sections to be coupled, at least one coupling member, adapted to engage at least one end of the barrel, section, and at least one elastomeric sealing ring adapted to be forced by the or each coupling member into at least one end of the barrel member and expanded radially outwardly and inwardly into tight sealing engagement within the end of the barrel member and around the circumference of the pipe section being coupled, wherein a substantially tangentially extending bolt is utilised to couple the or each respective coupling member to the barrel member, and means on the inside of the or each coupling member, and on the outside of the barrel member, to interact and progressively twist the or each coupling member along the barrel member to force the or each sealing ring into tight sealing engagement with the inside of the barrel member and around the circumference of the or each pipe section being coupled.

With the above defined coupling, only one or two bolts have to be tightened and by positioning them appropriately on top of the pipeline access to beneath the pipeline is not required, whilst an even force is applied to the or each sealing ring.

BRIEF DESCRIPTION OF THE DRAWINGS

One preferred embodiment of the invention will now be described with reference to the accompanying illustrations, in which:

FIG. 1 is a view from above of a replacement pipe section coupled to the ends of an existing pipeline utilising the known prior art pipe coupling at one end and the pipe coupling of the preferred embodiment of the present invention at the other end,

FIG. 2 is a perspective exploded view of the preferred pipe coupling of the present invention, and

FIG. 3 is a perspective view of the pipe coupling of FIG. 2 is an assembled condition with the pipeline sections omitted.

BEST MODES OF CARRYING OUT THE INVENTION

Turning to the illustrations, and in particular FIG. 1, there is shown an existing pipeline 10 from which a burst pipe section has been removed and replaced by a new pipe section 11. The existing pipeline may be metallic and the new replacement pipe section may be PVC having an internal diameter the same as that for the existing pipeline, but having a smaller external diameter.

The pipe coupling 12 at the left hand end of the illustration is a known form of a coupling, whilst the coupling 13 at the right hand end is a pipe coupling in accordance with the preferred embodiment of the present invention.

The known pipe coupling 12, as described previously, has a barrel member 14 adapted to bridge and surround the ends of the new and old pipe sections 11 and 10 respectively. The barrel member receives elastomeric sealing rings (not shown) within both ends to form seals between the inside of the barrel and the circumferences of the existing pipe section 10 and the new pipe section 11. The sealing rings are of an axially tapering configuration, and are forced into matingly internal tapered ends of the barrel member 14 by annular cylindrical coupling members 15 surrounding the pipe sections 10 and 11. The coupling members 15 are coupled together by axially extending bolts 16 passing through axially aligned holes 17 in outwardly extending lugs 18 carried by the coupling members. As the bolts 16 are progressively tightened, little by little, and in turn, to maintain an even force around the sealing rings, the sealing rings are forced into the ends of the barrel member, whilst axially compressing the sealing rings to expand then radially outwardly into tight sealing engagement within the ends of the barrel member and radially inwardly into tight sealing engagement around the circumferences of the pipe sections 10 and 11. As shown the axially extending bolts 16 are equally spaced (120°) around the coupling.

In contrast, the pipe coupling 13 of this preferred embodiment of the present invention, although also comprising a barrel member 19 adapted to bridge and surround the ends of the pipe sections 10 and 11, and a pair of coupling members 20, one at each end of the barrel member, and engaging and axially forcing and compressing a pair of axially tapered elastomeric sealing rings 21 into matingly axially tapered ends 19 a of the barrel member, and whereby to compress the sealing rings 21 so as to expand radially outwardly and inwardly into tight engagement ends 19 a of the barrel member 19, and the circumferences of the pipe sections 10 and 11, the coupling is structurally otherwise different. In order to move the coupling members 20 along the ends of the barrel member 19, and compress the sealing rings 21 therebetween, a single substantially tangentially extending bolt system 22 is used for each coupling member, and comprises a threaded shaft 23 extending through aligned holes 24 and 25 in radially outwardly extending lugs 26 and 27 on the coupling members 20 and the barrel member 19 respectively. Nuts 28 at either end of the threaded shaft 23, when tightened, served to twist the coupling members, by means of radially inwardly directed lugs 29 on the inside of the respective coupling members engaging radially outwardly directed and helically extending lugs 30 on the outside of the barrel member, whereby the coupling members move along the barrel member and compress the sealing rings whereby to expand them radially outwardly and inwardly into tight sealing engagement with the barrel member and circumferentially around the respective pipe sections 10 and 11. The bolts alternatively may be conventional bolts of the type having a head on a threaded shaft and nuts at only one end.

Reverting to FIG. 1 of the drawings, as the coupling member 20 surrounding the new pipe section 11 which is of a smaller diameter than in the existing pipeline 10, that coupling member twists further onto the end of the barrel section before the associated sealing ring radially expands sufficiently to engage in tight sealing engagement around the new pipe section 11. By providing sufficient spacing between the lugs 26 and 27 various external pipe diameters can be accommodated within the same installation, although the external diameter of the pipes in one installation may be different from those of another installation, whilst, as referred to above, the material of the new pipe section may be different from the existing pipe section.

The barrel and coupling member components 19 and 20 of the coupling 13 may be formed from ductile iron castings, whilst the elastomeric sealing rings 21 may be formed from conventional materials to achieve the sealing functions required.

It should be noted that the tightening of the bolt 16 required in the known pipe coupling requires a spanner to be swung in a substantially vertical plane (transversely of the pipeline axis), including down towards the bottom of the trench or hole which thus inhibits movement downwardly unless there is sufficient space beneath the pipeline. With the present invention the spanner or spanners are swung in the axial direction (longitudinally of the pipeline), and if the bolts are above the pipeline as in the case of the present invention, access (trench or hole depth) to beneath the pipeline does not inhibit spanner operation.

Although in the preferred embodiment described above the pipe coupling utilises two coupling members 20 and two elastomeric sealing rings 21, the barrel member in a new pipeline installation could alternatively be formed integrally with the end of one of the pipe sections (which may be a socket type configuration to receive spigot and configuration of the pipe section to be joined thereto) whereby only one coupling member and one elastomeric sealing ring are required to complete the coupling. 

1. A pipe coupling for coupling the ends of pipe sections together end to end, said coupling including a barrel member forming part of the end of one of the pipe sections, or adapted to bridge and surround the ends of the pipe sections to be coupled, at least one coupling member, adapted to engage at least one end of the barrel section, and at least one elastomeric sealing ring adapted to be forced by the or each coupling member into at least one end of the barrel member and expanded radially outwardly and inwardly into tight sealing engagement within the end of the barrel member and around the circumference of the pipe section being coupled, wherein a substantially tangentially extending bolt is utilized to couple the or each respective coupling member to the barrel member, and means on the inside of the or each coupling member, and on the outside of the barrel member, to interact and progressively twist the or each coupling member along the barrel member to force the or each sealing ring into tight sealing engagement with the inside of the barrel member and around the circumference of the or each pipe section being coupled.
 2. A pipe coupling as claimed in claim 1, wherein the barrel member is adapted to bridge and surround the ends of the pipe sections to be coupled, and two coupling members are provided, one for each end of the barrel ember and for the end of each pipe section, and two sealing rings are provided for positioning between each coupling member and an adjacent end of the barrel member whereby when the pipe coupling is assembled between the ends of the pipe sections and each coupling member is coupled to its adjacent end of the barrel member, by a said tangentially extending bolt for each coupling member, each sealing ring will be expanded radially outwardly and inwardly into tight sealing engagement within the barrel member and around the circumferences of the pipe sections being coupled.
 3. A pipe coupling as claimed in claim 1, wherein the means on the inside of the or each coupling member, and on the outside of the barrel member, to interact and progressively twist the or each coupling member along the barrel member, are one or more radially outwardly directed and helically extending lugs on the outside of the barrel member engaged by one or more radially inwardly directed lugs on the inside of the coupling member.
 4. A pipe coupling as claimed in claims 1, wherein the or each substantially tangentially extending bolt coupling the or each coupling member to the barrel member extends between radially outwardly directed lugs on the coupling member and the barrel member.
 5. A pipe coupling as claimed in any one of the preceding claims, wherein the or each elastomeric sealing ring are of axially tapering configuration and the adjacent end of the barrel member is matingly internally tapered.
 6. A pipe coupling, substantially as hereinbefore described with reference to the accompanying drawings.
 7. A pipe coupling as claimed in claim 2, wherein the means on the inside of the or each coupling member, and on the outside of the barrel member, to interact and progressively twist the or each coupling member along the barrel member, are one or more radially outwardly directed and helically extending lugs on the outside of the barrel member engaged by one or more radially inwardly directed lugs on the inside of the coupling member.
 8. A pipe coupling as claimed in claim 2, wherein the or each substantially tangentially extending bolt coupling the or each coupling member to the barrel member extends between radially outwardly directed lugs on the coupling member and the barrel member.
 9. A pipe coupling as claimed in claim 3, wherein the or each substantially tangentially extending bolt coupling the or each coupling member to the barrel member extends between radially outwardly directed lugs on the coupling member and the barrel member. 